Aces are available to come out of the bullpen. Situations with runners in scoring position become even more magnified. Nails are bitten and moods swing with every pitch. Plastic coverings and bottles of bubbly are prepared for both clubhouses.

Those are the distinguishing characteristics of an elimination game in October. And the National League Division Series are giving fans two Game 5s on Friday.

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The St. Louis Cardinals have yet to be completely shut down by any of the Philadelphia Phillies’ aces, allowing them to force a fifth game despite their ace, Chris Carpenter, lasting only three innings in the team’s Game 2 win.

In the other series, the home-field advantage has played out for two of the best home teams in the majors this season. And it has allowed the Arizona Diamondbacks to erase a 2-0 deficit and force a win-or-go-home Game 5 on the road against the Milwaukee Brewers.

A quick look at each NLDS Game 5 on Friday:

Cardinals at Phillies (8:37 p.m. ET, TBS)

Story line

Carpenter and Roy Halladay are close friends, former teammates and staff aces. And now they’ll face each other in one of the biggest games in each pitcher’s career.

Halladay won Game 1 in Philadelphia despite allowing three first-inning runs. He was as close to shutdown as any Phillies pitcher has been in the series, retiring the final 21 batters he faced and striking out eight in eight innings. Still, he entered the sixth inning trailing before the Phillies’ offense busted out for five runs (and finished with 11) to get the Cy Young contender the victory.

Carpenter had to pitch St. Louis’ first elimination game, the regular season finale, just to reach the postseason. It made him unavailable for Game 1 against Halladay, and he wasn’t effective (three runs on five hits and three walks) in Game 2 on short rest for the first time in his career. The short outing forced the Cardinals to use six relievers, but they got the win. In hindsight, manager Tony La Russa was wise to pull Carpenter when he did.

X-factor

Sorry, animal lovers, but the squirrel isn’t the X-factor. It is Cardinals left fielder Matt Holliday. Game 4 was Holliday’s first start of the playoffs because of a hand injury that still pains him and has sidelined him for most of the past three weeks. But Holliday singled, was hit by a pitch and scored twice in the Game 4 win.

If he remains a threat, St. Louis’ lineup becomes much deeper. It also could create situations where Halladay or Philadelphia’s relievers must pitch to Albert Pujols and Lance Berkman.

Prediction

Halladay stays something close to dominant and the Phillies ride him into the NLCS.

Diamondbacks at Brewers (5:07 p.m. ET, TBS)

Story line

It is extremely difficult to quantify how important it is for a team to play in its home park, but the Brewers’ 57 home wins led the majors this season and the Diamondbacks’ 51 were fifth. In this series, the road teams have been thoroughly outplayed and have yet to win a game, as nearly every categorical advantage and the momentum have been with the home team.

With the series moving back to Miller Park for Game 5, you must consider how comfortably the Brewers play in their own yard. The energy they gain from the home fans can’t be ignored, and neither can their swagger and confidence, which seemed to vanish as they shifted time zones and entered Arizona.

The Diamondbacks abused Milwaukee’s pitching in Games 3 and 4. To win Friday, Arizona must find a way to keep the momentum. That won’t be easy as the Brewers’ home-field advantage could be at an all-time high. Club officials have only half-joked that they probably could sell 100,000 tickets if they had the room.

X-factor

Starting pitching normally isn’t an X-factor because it usually is the primary factor. But given the way the home-team offenses have beaten down road-team pitching in this series, Arizona’s Ian Kennedy and Milwaukee’s Yovani Gallardo become key.

Gallardo pitched eight innings, allowed a run and struck out nine in a strong Game 1 outing, while Kennedy gave up four runs in 6 2/3 innings. Prince Fielder’s two-run homer in the seventh was Kennedy’s backbreaker.

This is simple: The team that gets better starting pitching will win.

Prediction

Arizona stays homer-happy, Kennedy pitches like an ace and the Diamondbacks advance to play the Phillies.